The invention relates to a lane assist for a motor vehicle, which lane assist can be activated and deactivated and enables a steering intervention on an axle using a superimposed steering system.
Lane assists belong to the active steering systems of motor vehicles, in which a mechatronic system is provided to adjust the steering angle of the steered wheels.
Lane assists aid the driver by taking over the lateral guidance of the vehicle in the activated state. One or more optical sensors survey the surroundings of the vehicle, and the lane assist guides the vehicle within a certain driving envelope which has been established on the basis of the survey of the surroundings. The driving envelope is an area within a lane.
The operation of the Lane assist requires knowledge of the future travel path (trajectory) of the vehicle. The information about the future travel path would also be useful for other driver assist systems. To date, the future travel path is predicted on the basis of the current steering angle. At high speeds, e.g. on an expressway, the steering angle required for a great radius of curve is very small. In addition, the driver constantly carries out a shaky, jerky steering motion which is superimposed on the steering angle signal actually needed. These interferences, which play no significant part on the future trajectory, are in the same order of magnitude as the steering wheel angle signal required for determining the course of the trajectory. Even with high-resolution of the steering angle sensor, the result is still a very poor signal/noise ratio which does not allow prediction of a stable and precise trajectory.